Toxoplasma gondii is an intracellular protozoan parasite capable of causing chronic infection by forming persistent cysts in the brain. Despite its global burden, no approved vaccine exists. Virus-like particle vaccines expressing microneme protein 8 (MIC8) or apical membrane antigen 1 (AMA1) of T. gondii have previously shown efficacy. In this study, we generated recombinant vaccinia viruses (rVVs) expressing MIC8 and AMA1 and evaluated their efficacy against T. gondii ME49 infection. BALB/c mice were intramuscularly immunized with a combination of MIC8 and AMA1 rVVs and challenged orally with T. gondii ME49. Immunization with MIC8+AMA1 rVVs produced a significant increase in T. gondii-specific IgG. Splenocyte analysis revealed robust activation of CD4+ and CD8+ T cells, as well as expansion of memory B cells. The immunized group exhibited an 89.6% reduction in brain cyst count, with significantly improved survival compared to the control group. These findings demonstrate that combining the antigens MIC8 and AMA1 using a vaccinia virus platform can effectively promote both humoral and cellular immunity, supporting its potential as a vaccine strategy against T. gondii ME49.
Ernest Mazigo, Hojong Jun, Wang-Jong Lee, Johnsy Mary Louis, Fadhila Fitriana, Jadidan Hada Syahada, Fauzi Muh, Feng Lu, Md Atique Ahmed, Seok Ho Cha, Wanjoo Chun, Won Sun Park, Se Jin Lee, Sunghun Na, Joon-Hee Han, Nyalali Kija, Smart Geodfrey, Eun-Teak Han, Jim Todd, Alphaxard Manjurano, Winifrida Kidima, Jin-Hee Han
Parasites Hosts Dis 2025;63(1):57-65. Published online February 25, 2025
As many countries implement different programs aimed at eliminating malaria, attention should be given to asymptomatic carriers that may interrupt the progress. This was a community-based cross-sectional study conducted in Tanzania from December 2022 to July 2023 within 4 villages from each of the 3 regions, Geita and Kigoma, which are high malaria transmission, and Arusha, which is low transmission. Malaria was diagnosed in asymptomatic individuals aged 1 year and older using the malaria rapid diagnostic test and light microscope. A total of 2,365 of 3,489 (67.9%) participants were enrolled from high-transmission villages. The overall prevalence was 25.5% and 15.8% by malaria rapid diagnostic test and light microscope, respectively. Using the respective tools, the prevalence was significantly higher at 35.6% (confidence interval (CI)=23.6–49.9) and 23.1% (CI=16.2–35.1) in the high-transmission regions (Geita and Kigoma) compared with 2.9% (CI=1.1–3.5) and 1.1% (CI=0.7–1.8) in the low-transmission region (Arusha). Children younger than 15 years and males accounted for the greatest proportion of infections. In the study area, the prevalence of asymptomatic cases was higher than that of reported symptomatic cases in health facilities. We hypothesize that these parasite reservoirs may contribute to the persistence of malaria in the country. Therefore, to achieve comprehensive malaria control in the country, the surveillance and screening of asymptomatic malaria cases are vital.
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Hidden reservoirs of infection: prevalence and risk factors of asymptomatic malaria in a high-endemic region of Zambia Wisdom Silwamba, David Chisompola, John Nzobokela, Martin Chakulya, Lombe Kabwe, Kingsley Tembo Malaria Journal.2025;[Epub] CrossRef
Emergence of chloroquine-sensitive
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and rising resistance to first-line artemisinin partner drugs in Malawi
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Micro-geographic variation in antigenic diversity of PfEBA-175 region II in asymptomatic Plasmodium falciparum infections in Tanzania Jadidan Hada Syahada, Wang-Jong Lee, Hojong Jun, Johnsy Mary Louis, Fadhila Fitriana, Fauzi Muh, Feng Lu, Md Atique Ahmed, Sunghun Na, Wanjoo Chun, Won Sun Park, Bo-Young Jeon, Eun-Teak Han, Jim Todd, Alphaxard Manjurano, Winifrida Kidima, Ernest Mazigo, Frontiers in Immunology.2025;[Epub] CrossRef
Human infections due to the monkey malaria parasite Plasmodium knowlesi is increasingly being reported from most Southeast Asian countries specifically Malaysia. The parasite causes severe and fatal malaria thus there is a need for urgent measures for its control. In this study, the level of polymorphisms, haplotypes and natural selection of full-length pkmsp8 in 37 clinical samples from Malaysian Borneo along with 6 lab-adapted strains were investigated. Low levels of polymorphism were observed across the full-length gene, the double epidermal growth factor (EGF) domains were mostly conserved, and non-synonymous substitutions were absent. Evidence of strong negative selection pressure in the non-EGF regions were found indicating functional constrains acting at different domains. Phylogenetic haplotype network analysis identified shared haplotypes and indicated geographical clustering of samples originating from Peninsular Malaysia and Malaysian Borneo. This is the first study to genetically characterize the full-length msp8 gene from clinical isolates of P. knowlesi from Malaysia; however, further functional characterization would be useful for future rational vaccine design.
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Plasmodium knowlesi: the game changer for malaria eradication Wenn-Chyau Lee, Fei Wen Cheong, Amirah Amir, Meng Yee Lai, Jia Hui Tan, Wei Kit Phang, Shahhaziq Shahari, Yee-Ling Lau Malaria Journal.2022;[Epub] CrossRef
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